Amazon SageMaker
Developer Guide

Step 3.2: Download, Explore, and Transform the Training Data

Now download the MNIST dataset to your notebook instance. Then review the data, transform it, and upload it to your S3 bucket.

You transform the data by changing its format from numpy.array to RecordIO. The RecordIO format is more efficient for the algorithms provided by Amazon SageMaker. For information about the RecordIO format, see Data Format.